Herpesviruses are widespread in nature and associated with both latent and neoplastic infections. At least five, including herpes simplex viruses 1 and 2, herpes zoster virus, cytomegalovirus, and Epstein-Barr virus, infect man and three of these are implicated as etiologic agents in human neoplasias. The objective of this research is to examine in greater detail the flow of events involved in the assembly and maturation of herpes simplex virus, and to identify specific gene functions that regulate this process. Intermediates in virus assembly will be isolated and their composition and topological organization analyzed by sensitive techniques of two-dimensional polyacrylamide gel electrophoresis, two-dimensional peptide analysis, and in vitro surface radiolabeling. In addition, efforts will be made to establish the role of modifications such as protein phosphorylation and cleavage in the assembly process. The general rationale of these experiments is that knowledge of what occurs during productive infection may lead to a better understanding of what transpires in the course of abortive infection, from which virus-transformed cells might ultimately be derived.